The present invention relates to keyboards for computers, electronic typewriters, data entry units, and other similar apparatus. In particular this invention provides a unique keyboard comprised of three angled sets of keys which are ergonomically positioned to form a pyramid-shaped keyboard. The present invention allows an improved and more natural hand, arm and position when typing, and thereby reduces repetitive stress injuries (RSI) such as carpal tunnel syndrome (CTS), flexor tendinitis, extensor tendinitis, and DeQuervain's disease.
Frequent use of a conventional horizontal keyboard results in injuries due to the unnatural angle the hands are required to assume to operate the keyboard when typing. An operator of a conventional keyboard must rotate his arms so as to dispose his hands are in a palms-down position, by pronation, and align his fingers with the rows of keys by twisting each hand outward at the wrist, by ulnar deviation. Conventional horizontal keyboards result in the operator's arm and hand muscles operating outside their natural and ideal range, and thus functioning poorly and increasing risks of injury. Tendons and nerves are adversely affected, and over time this abuse can lead to repetitive stress injuries. For example, an operator of a conventional horizontal keyboard often types with bent wrists, resulting in irritation and bunching of the sheaths surrounding the tendons. This bunching affects the sensitive median nerve in the carpal tunnel, and may lead to carpal tunnel syndrome (CTS). Symptoms of CTS are "shooting" pains from the wrists to the forearms, palms or fingers. In extreme cases, CTS and other RSI are permanently debilitating. In a significant number of cases, repetitive stress injuries force keyboard operators or other workers which frequently use a keyboard to an alternative type of employment that does not require use of a keyboard.
Computer keyboard injuries annually afflict about 185,000 office and factory workers and cost companies about $20 million. Presently, annual worker's compensation payments for these injuries is approximately $1.1 billion. The competitive advantages of data processing indicate that computer use, and therefore the number, frequency and cost of repetitive stress injuries due to conventional keyboards, is certain to increase. Over the last decade the number of employees using conventional computer keyboards in the United States has increased from approximately 5 million to 50 million. In total, there are presently about 120 million keyboard operators in the United States. To reduce the occurrence of CTS and other repetitive stress injuries, a keyboard should alleviate the underlying causes of repetitive stress injuries. Such an improved keyboard, which is realized in the present invention, must relieve muscle and tendon strain, lessen or reduce wrist deviation, reduce or eliminate forearm pronation, reduce the distance fingers must travel and lessen the force necessary to the keys. Dr. David Thompson, a professor emeritus at Stanford University has found that muscles worked less with a keyboard on a 30 degree tilt and significantly less with a 60 degree tilt. Dr. Thompson stated that it took about 40 percent more muscle effort to type on a flat linear keyboard than on a keyboard with a 60 degree tilt. Additionally, muscles worked less with straight wrists than when the wrists are bent. Dr. Thompson explained that the harder muscles work the more likely they are to become overworked and this increases the possibility the user will become fatigued, as well as the likelihood that repetitive stress injuries may occur.
There is evidence that a keyboard user faces a higher risk of CTS when performing repetitive actions in a cold environment. H. C. Chiang, S. S. Chen, H. S. Yu and Y. C. Ko in The Occurrence of Carpal Tunnel Syndrome in Frozen Food Factory Employee, Kao-Hsiung I Hsueh Ko Hsueh Tsa Chih 6(2):73-80 (Feb. 1990) found that employees who exposed to a cold environment while performing repetitive actions were more likely to have suffer from CTS than those who had no exposure to cold while performing repetitive actions, based upon CTS finds of 40.54% and 37.19%, respectively, for the individuals studied.
It is known that the body's muscles function better and are less prone to injury in a relatively warm environment. However, the temperature in the typical office environment is kept relatively cold, in order to promote mental alertness. Consequently, when typing in most office environments the hands are often cold and subject to reduced blood flow. Like an athlete who faces increased risk of injury competing in a cold environment, the typist may also face an increased risk of hand or wrist injury when typing in a cold office environment.
A number of prior art keyboard designs have been proposed in an attempt to reduce RSI. This is seen in, for example, U.S. Pat. Nos. 4,378,553 to McCall and 4,661,005 to Lahr, disclose a design where the conventional QWERTY keyboard layout is split into two separate pieces, allowing the operator to space each horizontal keypad at a comfortable interval. Other designs angle a horizontal planar keyboard into a V shape or chevron design as illustrated by U.S. Pat. Nos. 5,156,475 to Zilberman and 5,129,747 to Hutchison. Other designs split the keyboard and rotate each split half of the keypad into a vertical position as disclosed in U.S. Pat. Nos. 5,160,919 to Mohler and 5,137,384 to Spencer. These designs purport to reduce wrist deviation and hand pronation.
U.S. Pat. No. 4,597,681 to Hodges discloses an "Adjustable Keyboard" divided into two sets of keys that are adjustable relative to each other in both a horizontal and vertical manner. FIGS. 3 and 4 of Hodges indicates that the split keyboard may be pivotally adjusted to form an inverted V. Another keyboard design is disclosed in U.S. Pat. No 5,067,834 to Szmand which discloses an "Input Keyboard Apparatus for Information Processing Device and Other Keyboard Devices." The input keyboard of Szmand includes a left and right keyboard each mounted on a telescopic shaft attached to a base support plate. The two keyboards form a generally inverted V shaped spacing with each keyboard having a front-to-back inclination and a lateral side inclination with universal pivots permitting individual settings for an operator. The keyboard connecting pivot unit is releasable to allow lateral spacing of the keyboard.
There are a number of deficiencies associated with the prior art designs proposed by Hodges' and Szmand's. Those designs provide no hand support once the keyboard is angled in an inverted V shape, possibly causing additional strain to the keyboard operator. In addition, many operators do not know which keys must be pressed to obtain the shifted numeric characters, i.e., "@", "", ".about.", "&", and "+", and in many cases even which keys must be pressed to obtain the number keys. The fact that the keys in Hodges and Szmand are disposed in an angle perpendicular to the operator may make reading of the individual keytop indicia by the operator difficult and time consuming, thereby reducing the speed and possibly the performance of the operator. With the Hodges and Szmand designs, the keyboard operator must still extend or move his entire hand, not just the fingers, in order to operate the function and number keys. Such movement may result in the incorrect positioning of the hands such as bending the wrist, thereby increasing the likelihood of repetitive stress injuries. Furthermore, both Hodges' and Szmand's designs fail to incorporate a trackball/mouse feature, so the operator's hand must leave the keyboard to use an auxiliary trackball/mouse.